To provide a system capable of measuring accurately a contact angle of a droplet discharged from an ink jet head and impacted onto a substrate.

This observation system 1 has the ink jet head 30; the first observation unit 10 including the first imaging device 11 for observing the flying state of the droplet discharged from a nozzle 31 of the ink jet head, and the first imaging lens 12; the second observation unit 20 including the second imaging device 21 for observing from the side, a state after the droplet discharged from the nozzle 31 of the ink jet head is impacted onto the target substrate 2, and the second imaging lens 22; and a head moving mechanism 50 for moving the ink jet head 30 along the first line X1 connecting a focal position 13 of the first imaging lens 12 to a focal position 23 of the second imaging lens 22.